FILE PHOTO: Yazidi member of the Iraqi Parliament, Vian Dakhil, arrives for the opening night of the Women in the World summit in New York April 22, 2015. REUTERS/Lucas Jackson

ERBIL (Reuters) - As Iraqi forces pressed their offensive to retake Tal Afar on Monday, a Yazidi politician urged them to quickly rescue the many Yazidi men, women and children still believed to be held captive in the city by Islamic State militants.

Vian Dakhil, a member of the Iraqi parliament, said the fate of children who had been kidnapped, sold or had their identities changed was of particular concern.

Dakhil won international prominence in 2014, when she stood up in parliament and begged for help for the religious minority that had come under militant attack in Sinjar.

The Yazidi area in northern Iraq had previously been home to about 400,000. In a matter of days, more than 3,000 Yazidis were killed and about 6,800 kidnapped, either sold into slavery or conscripted to fight for Islamic State.

More than 3,000 women and children are still believed to be held captive by Islamic State, according to community leaders.

“We ask the leaders of the military and security forces to take precautions regarding the large number of kidnapped Yazidis still present in Tal Afar and its surrounding villages,” Dakhil said in a statement.

She urged the advancing Iraqi force to rescue the enslaved Yazidis “as soon as possible”.

Dakhil asked for rescued Yazidis to be separated from other fleeing civilians and not be sent to refugee camps.

Tal Afar is one of the few remaining Islamic State strongholds in northern Iraq.

Between 10,000 and 40,000 people are thought to remain in Tal Afar and its surrounding villages, with more than 30,000 having fled since April, according to U.N. estimates.

Important for its position along the supply route between Mosul and Syria, it has produced some of Islamic State’s most senior commanders and was cut off from the rest of IS-held territory in June.

About 2,000 battle-hardened militants remain in Tal Afar, according to U.S. and Iraqi military commanders.

Several surrounding villages and roads had already been retaken by the second day of the offensive, with a view to trapping the remaining militants in the city itself. A Federal Police spokesman said a network of tunnels had also been seized.

“We are cutting off the arms of the octopus to make it weaker and vulnerable,” Colonel Kareem al-Lami of the Iraqi army’s 9th Division, said.